The present invention in various embodiments relates to an illuminating device for a vehicle, in particular a motor vehicle, for realizing an asymmetrical light distribution. Asymmetrical light distribution provides greater illumination depth on the side of the road traveled on by the vehicle itself, hereinafter the vehicle's side of traffic, than on the side of the road traveled on by oncoming traffic, hereinafter the side of oncoming traffic. The illuminating device includes at least two headlights that are arranged in a forward area of the vehicle, of which at least a first headlight is arranged on the vehicle's side of traffic and at least a second headlight is arranged on the side closer to oncoming traffic.
The present invention in some embodiments also relates to a control device for controlling an illuminating device of the aforementioned type.
The illuminating device according to embodiments of the present invention can be used for both right-side driving as well as for left-side driving. In the case of right-side driving, the vehicle's side of traffic corresponds to the right-hand side of the road, and the side of oncoming traffic corresponds to the left-hand side of the road. Conversely, in the case of left-side driving, the vehicle's side of traffic corresponds to the left-hand side, and the side of oncoming traffic corresponds to the right-hand side. If, in the present application, only the right side or the left side is mentioned, statements made in connection with the side in question are also valid correspondingly for the other side.
Asymmetrical light distribution can be applied to low beam, fog light, or other similar lighting functions. In asymmetrical light distribution, the greatest proportion of the light emitted by the illuminating device is limited to an area below the light-dark boundary line. The purpose of asymmetrical light distribution is, on the one hand, to achieve the greatest possible illumination depth on the vehicle's side of traffic and, on the other hand, not to blind other road users on the side of oncoming traffic.
On a measuring screen arranged in the beam path of the illuminating device, it can be seen that, on the side of oncoming traffic, the light-dark boundary of an asymmetrical light distribution, as it is generally encountered in Europe, includes an essentially horizontal partial area, which extends roughly up to a vertical central plane that runs through the optical axis of the headlight. Proceeding from the intersection between the horizontal partial area and the vertical central plane, the light-dark boundary on the vehicle's side of traffic rises at an angle of roughly 15°.
In contrast, the light-dark boundary of the light distribution that is generally encountered in North America produces on a measuring screen horizontal partial areas both on the vehicle's side of traffic as well as on the side of oncoming traffic, the partial area of the light-dark boundary that is on the vehicle's side of traffic being arranged so as to be higher than the partial area on the side of oncoming traffic. The light-dark boundary between the two horizontal partial areas produces a diagonally rising line. Therefore, a light-dark boundary of this type represents a Z-shaped line. As a result of asymmetrical light distribution, on the roadway in front of the vehicle there is on the vehicle's side a greater illumination depth of light emitted from the illuminating device than on the side of oncoming traffic.
The asymmetrical light distribution having the light-dark boundary is generated through the cooperation of the at least two headlights of the illuminating device. In this context, the headlights of the illuminating device are not required to each produce identical light distributions, which are then superimposed to form the asymmetrical light distribution. Rather, it is quite conceivable that one of the headlights generates one specific partial area of the asymmetrical light distribution and the other headlight generates another partial area of the asymmetrical light distribution, the light-distribution partial areas generated by the individual headlights then being superimposed to create the asymmetrical light distribution of the illuminating device.
To improve the illumination of the roadway in front of the vehicle during cornering, various systems are known from the related art that make it possible to horizontally shift the direction at which light exits both headlights as a function of the radius of the curve (a so-called adaptive or dynamic cornering light system). For example, the direction at which the light exits a headlight can be shifted by swiveling a headlight module of the headlight. In these well-known dynamic cornering light systems, swivel angles are realized in a range of roughly +/−10° to +/−15°. In addition, the direction at which light exits the headlights can also be horizontally shifted as a function of the speed of the vehicle.
The advantages of cornering light systems of this type lie in increasing the recognition distance for objects on the roadway, thereby improving traffic safety. In addition, as a result of the increased depth of the light beams emitted by the illuminating device, the act of driving is less fatiguing. Furthermore, there is also greater comfort as a result of increasing the feeling of safety for the driver of the vehicle. Finally, the system also has a positive influence on driving enjoyment, because the motion of the headlights responds directly to the steering angle, i.e., to the parameters of the driving dynamics.
One disadvantage in the known system for horizontally swiveling the headlights during cornering is the expense required in adding mechanical components, bearings, and drives to the headlight. For example, a drive for horizontally swiveling the headlight or the headlight module can be configured as an electric motor, a proportional motor, a stepper motor, a piezo actuator, or even as a hydraulic or pneumatic drive. In addition, a control unit must be provided, which is connected to the headlights for shifting the direction at which light exits and which has a means for controlling the headlight module. Alternatively, a pre-existing control unit may be functionally expanded in an appropriate manner.
The suspension and support of the headlight modules that generate the headlights' asymmetrical light distribution are associated with significant expense because it is necessary both technically and functionally to arrange for the headlight modules to swivel vertically in the context of headlight leveling control and for the vertical swiveling to be superimposed on a horizontal rotational motion at a relatively large displacement angle and at a relatively great displacement speed, and to reliably guarantee this for all driving states of the vehicle. Thus, for example, requirements regarding vibration resistance no less than requirements for durability must be satisfied over a large number of swiveling cycles for the entire service life of the vehicle. Furthermore, an additional frame system must be provided for suspending and supporting the headlight modules, as well as additional drives for carrying out the horizontal swiveling. A fail-safe function must also be realized to satisfy the requirements of law in the event of failure, requiring, inter alia, sensors for monitoring the swivel position of the headlight modules. All of these additional requirements for mechanical and electrical components and for the control unit result in the illuminating devices of known cornering light systems being relatively complicated in design, cumbersome, and expensive.
An objective of the present invention, arising from the foregoing considerations, is to design and refine an illuminating device of the type cited above such that, on the one hand, during cornering the illumination depth of the light emitted by the illuminating device is increased, whereas, on the other hand, the illuminating device and its headlights are still configured in as simple, compact, and cost-effective a way as possible.
To achieve this objective, taking the illuminating device of the type indicated above as a point of departure, it is proposed that during cornering the direction of light exiting the first headlight be fixedly oriented straight ahead, irrespective of the direction and the radius of the curve, and that the direction of light exiting the second headlight be horizontally shifted at least toward the side of oncoming traffic as a function of the direction and the radius of the curve.
In embodiments of the present invention, it has been taken into account that, by asymmetrically illuminating the roadway in front of the vehicle on the basis of an asymmetrical light distribution and without additional technical efforts or measures being undertaken, the course of the roadway along a curve that bends in the direction of the vehicle's side of traffic is better illuminated than the course of the roadway along a curve that bends in the direction of oncoming traffic. As a result of the asymmetrical line of the light-dark boundary having the rising partial area on the vehicle's side of traffic, the aforementioned already applies to headlights that do not swivel horizontally. This characteristic of an illuminating device that has asymmetrical light distribution is exploited in embodiments of the present invention in that the headlight of the illuminating device arranged on the vehicle's side of traffic is configured so as not to be able to swivel. Thus the optical axis of this headlight, both in driving straight ahead as well as in cornering, is fixedly oriented straight ahead, i.e., roughly parallel to the longitudinal axis of the vehicle.
In an illuminating device according to an embodiment of the present invention, only the headlight that is arranged on the side of oncoming traffic is designed so as to be able to swivel horizontally. To achieve the deepest and best possible illumination of the roadway while cornering in the direction of the side of oncoming traffic, it is sufficient if the headlight arranged on the side of oncoming traffic can only be swiveled toward the side of oncoming traffic. It is therefore conceivable that during cornering in the direction of the vehicle's side of traffic the headlight that is arranged on the side of oncoming traffic not be swiveled but that the greater illumination depth of the emitted light on the vehicle's side of traffic due to the asymmetrical light distribution rather be exploited for more powerfully illuminating the roadway along the curve. Of course, the headlight arranged on the side of oncoming traffic may be swiveled both to the left as well as to the right so as to actively increase the illumination depth of the light emitted by the illuminating device on both left-hand and right-hand curves.
In an illuminating device according to embodiments of the present invention, only the headlight that is arranged on the side of oncoming traffic is configured so as to be able to swivel horizontally. In contrast, the headlight that is arranged on the vehicle's side of traffic is fixedly mounted on the vehicle so as not to be able to swivel horizontally. This means that the headlight on the vehicle's side of traffic can be designed in a particularly simple, compact, and cost-effective manner, since there is no need for additional mechanical and electrical components to effect horizontal movement. In addition, it is possible to simplify the control unit for controlling the horizontal swivel motion of the headlights such that the control unit is connected only to the headlight arranged on the side of oncoming traffic and such that in the control unit only one control program is provided for controlling the horizontal motion of the headlight arranged on the side of oncoming traffic. An illuminating device according to embodiments of the present invention therefore basically represents a simplification such that, in contrast to the related art, where in order to realize a dynamic cornering light function both headlights on both sides of the vehicle can be swiveled both to the right and the left, only the headlight of the illuminating device that is arranged on the side of oncoming traffic can be swiveled and only in one direction, i.e., toward the side of oncoming traffic.
According to one advantageous refinement in an embodiment of the present invention, it is proposed that the second headlight be able to be swiveled horizontally as a function of the direction and the radius of the curve both in the direction of oncoming traffic as well as in the direction of the vehicle's side of traffic.
According to one preferred embodiment of the present invention, it is proposed that the second headlight be configured as a projector beam headlight. Alternatively, it is proposed that the second headlight be configured as a reflection headlight. Usually the first headlight and the second headlight of the illuminating device are both configured either as projector beam headlights or as reflection headlights.
According to a further preferred embodiment of the present invention, it is proposed that the second headlight have a light source that is configured as an incandescent lamp, a gas discharge lamp, or a luminous area of an optical fiber. In most cases, the same type of light source is used in both the first and second headlights of the illuminating device. The advantages of the present invention in various embodiments are especially significant in illuminating devices that have incandescent lamps as light sources (so-called halogen headlights), because lower costs are specially pronounced in headlights of this type. In addition, illuminating devices of this type are used especially in smaller and less expensive vehicles, where the particularly compact headlight on the vehicle's side of traffic results in significant savings of space in the front area of the vehicle. The space that is saved can then be used for other illumination or control functions.
As a further solution to the problematic of the present invention, taking the control unit of the type cited above as a point of departure, it is proposed that the control unit have means for horizontally shifting the direction at which light exits the second headlight, the means being connected only to the second headlight and, during cornering, horizontally shifting the direction at which light exits the second headlight at least toward the side of oncoming traffic as a function of the direction and the radius of the curve, the direction at which light exits the first headlight at the same time being fixedly oriented straight ahead, irrespective of the direction and the radius of the curve.
The swiveling means are configured, for example, as a control program that runs on a computer, in particular on a microprocessor of the control unit, and that is programmed for executing a method according to an embodiment the present invention, assuming that it runs on a computer. The swiveling means are preferably stored on an electrical storage medium, for example a random-access-memory (RAM), a read-only-memory (ROM), or a flash memory. For executing the control program, it is called up from the storage medium and is transmitted to the computer either totally or partially.
According to one advantageous refinement of the present invention, it is proposed that, during cornering in the direction of the side of oncoming traffic, the swiveling means horizontally shift the direction at which light exits the second headlight in the direction of the side of oncoming traffic as a function of the direction and the radius of the curve.
According to one preferred embodiment of the present invention, it is proposed that, during cornering in the direction of the vehicle's side of traffic, the swiveling means horizontally shift the direction at which light exits the second headlight in the direction of the vehicle's side of traffic as a function of the direction and radius of the curve. Even then the second headlight does not require a fail-safe sensor.
Finally, it is proposed that the swiveling means shift the direction at which light exits the second headlight as a function of a speed of the vehicle.
Further features, potential applications, and advantages of the present invention in various embodiments will become apparent from the following description of exemplary embodiments of the present invention, which are represented in the drawing. In this context, all features that are described or represented alone or in any combination are the subject matter of the present invention regardless of their summary in the patent claims or their previous mention and regardless of their formulation or depiction in the description or the drawing.